HI again, Richard,
I've been kicking around the idea of molding up some other (non-
musical) parts for awhile, and this little episode has finally pushed
me over the edge. I went ahead and ordered some molding silicone,
release agent, and black urethane casting resin. I imagine I'll have
all the "fixins" by next weekend. Naturally I had to order enough to
make 200 slider knobs, but if I have good luck with my parts I'll be
glad to make you a copy of yours... although all that shipping back
and forth across the pond could make this a very long process. I've
been working with composites for a number of years, although this
will be my first venture into do-it-yourself injection molding, so
I'm looking forward to the new challenge. My slider knob has a 1mm
thick white (pointer) line that runs horizontally around its
circumference that adds a bit more challenge to the project... I'm
thinking I'll make an initial cast part into which I can mill the 1mm
slot around its middle (it's nice to have a machine shop at hand) and
use that to create a new exterior mold, then use an actual knob to
mold the rear, with the notch for the slider shaft. One advantage to
this approach is that the parting line will be at the exact back of
the knob, so any flash will be removed invisibly. Once the black
part is released from the mold I can apply some white casting resin
to the slot, sand away the excess and polish off the whole thing once
it's all cured up. A ton of work to duplicate a 50 cent part, but at
least it will be right. I just hope the casting resin's black
matches the black of the original knob. We'll see.
<marv>
--- In oldsynths@yahoogroups.com, "RMC" <rmc@r...> wrote:
> if I do get anywhere with making a mould, I will let you know.
Thanks for
> getting in touch - at least we both know we aren't alone in our
feeble
> quest!
>
> Cheers
>
> Richard Craven
> England